Thank you for the citation. The following passage may be of particular interest as to the role of UV reflectance of spider webs:

Bird vision is more similar to that of humans, but it often—like that of insects—extends into the UV (Finger & Burkhardt 1994).Consequently, stabilimenta are probably quiteconspicuous to birds. Since birds are only rarely the prey of spiders, it may be concluded that the main function of stabilimentum is probably deterrence against birds, rather than attraction of prey; thus conﬁrming the studies of e.g., Lubin (1975), Horton (1980), Eisner & Nowicki (1983), Schoener & Spiller (1992) and Blackledge & Wenzel (1999). However, before any ﬁnal conclusions can be drawn, much more must be learned about the way different potential prey and predators perceive spiders and their webs.